The term "television receiver" as used herein includes television receivers having a display device (commonly known as television sets), and television receivers without a display device, such as videocassette recorders (VCR's).
The term "television receiver" as used herein also includes television monitor/receivers having an RF tuner and baseband signal input circuitry.
Many modern television receivers have picture-in-picture (PIP, or PIX-IN-PIX) capability, that is, the capability to receive video signals from two different sources and combine them to produce a signal which when displayed includes a first program in a main viewing area, and a second program in a secondary (inset) viewing area of the same display screen.
It is known in the art to produce a multi-picture (multipix) display be generating a 3.times.3 or 3.times.4 matrix of small still (i.e., freeze-frame) pictures. These small still pictures are produced by storing a series of "snap-shot-like" still images to form a display of pictures having a fixed time interval between frames.
It is also known to use the multipix technique to display an array of still inset images representative of the programs on each of the channels included in a scan list stored in memory. These messages are produced by initiating the tuning of a channel, waiting a predetermined time while the tuner performs the the tuning operation, storing a frame of video from that channel, tuning the next channel from the scan list, and so on. A 3.times.4 matrix of images of this type, captured from 12 television channels, is illustrated in prior art FIG. 3. Such a system is known from the RCA VPT-695 videocassette recorder, sold by Thomson Consumer Electronics, Inc., Indianapolis, Ind.
In the U.S., television channels are allocated to respective radio frequencies in accordance with one of three different standards. Broadcast television frequencies are assigned and regulated by the Federal Communications Commission (FCC). Cable companies, however, employ a second standard by which some cable channel frequencies are slightly offset from the FCC broadcast frequency standards, or a third standard by which some cable channel frequencies are grossly offset from the FCC broadcast frequency standards. So-callled cable ready television receivers use a search algorithm to locate the offset cable channels. Not surprisingly, tuning a grossly offset cable channel via a search algorithm takes longer (up to approximately 1 second total time), than tuning an FCC standard broadcast channel. Understandibly, the tuner settling time delay of approximately 1 second used by the RCA VPT-695 allows for the longest tuning time required. Thus, in that system, filling a 3.times.4 matrix with freeze-frame images from different channels takes about 12 seconds, which may be an undesirably long time for the user to wait.